排序兩個表（全連接）

Question

即時連接表所示：

select * from tableA a full join tableB b on a.id = b.id 

但輸出應該是：

1. 行沒有空字段
2. 一行TableB中
空字段
3. 在表A中有空字段的行

喜歡：

a.id a.name b.id b.name 
5 Peter 5 Jones 
2 Steven 2 Pareker 
6 Paul null null 
4 Ivan null null 
null null 1 Smith 
null null 3 Parker 

Answer 1

create table a(id number, name varchar2(10)); 
insert into a(id, name) values(5, 'Peter'); 
insert into a(id, name) values(2, 'Steven'); 
insert into a(id, name) values(6, 'Paul'); 
insert into a(id, name) values(4, 'Ivan'); 

create table b(id number, name varchar2(10)); 
insert into b(id, name) values(5, 'Jones'); 
insert into b(id, name) values(2, 'Pareker'); 
insert into b(id, name) values(1, 'Smith'); 
insert into b(id, name) values(3, 'Parker'); 

select * from a full join b on a.id = b.id 
order by 
    case 
    when a.id is not null and b.id is not null then 0 
    when a.id is not null and b.id is null then 1 
    when a.id is null and b.id is not null then 2 
    else 3 
    end 
;